Computers have been developed which are the size of credit cards. A break through is required with respect to the miniaturization of character input devices before the full potential of credit card computers can be realized.
The character input device most commonly employed in connection with computers remains the Qwerty keyboard as developed for use in typewriters almost a century ago. Attempts have been made to miniaturize this keyboard, however these attempts have not met with success. A miniature Querty keyboard on which the keys are activated with the tip of a pen is not efficient, as the human hand obscures the keyboard and speed is lost when the operator must "hunt and peck" the multiplicity of keys. Efforts have been made to miniaturize the keyboard by reducing the number of keys required. This can be done by having characters entered by pressing two or more keys in combination. The problem with this type of keyboard is that it still is limited by the size of the fingers of the human hand required to activate the keys and a reduction in the number of keys inevitably reduces the number of potential characters, thereby limiting use.
Efforts have been made to develop handwriting decoders, as an alternative to keyboards. These input devices are capable of "reading" a person's printing or handwriting. In theory, this would be an ideal system as it would have all the flexibility and portability of handwriting combined with the speed and clarity of typing. In practice these devices have met with numerous problems. All operable devices are complex as the characters they must decode tend to vary with the handwriting style of the operator. The size of the input mechanism is necessarily limited by the smallest character a human can accurately and consistently write. Interactive feedback is required due to the possibility that characters may not be recognized.